I. Basic Concepts

A. Ecology: the study of the relationships between organisms and their environments

B. Biosphere: the portion of the earth that is capable of supporting life

C. Ecosystem: the portion of the biosphere where living and non-living things interact

1. Biotic: living part (plants and animals)2. Abiotic: non-living part (environment)

D. Community: all of the organisms living together in a particular area

E. Population: all of the organisms of one species which are in the community

F. Habitat: the place within the community where the population lives

G. Niche: the function an organism has in its environment

II. Dynamics of the Ecosystem

A. Energy relationships

1. Producers: make food (autotroph)a. Photosynthesis is used to make foodb. Plants are producers

2. Consumers: eat food (heterotroph)a. Respiration is used to obtain energy from foodb. Types of consumers

1. Primary consumer: eats a producer (herbivore)2. Secondary consumer: eats a primary consumer (carnivore)3. Tertiary consumer: eats a secondary consumer

c. Decomposers: break down dead things into basic nutrients (reducer)1. Provide basic nutrients which the producers turn into food2. Remove the waste from the ecosystem (detritivores/scavengers)

3. Food chain a. Def: A series of producers and consumersb. Food web: A complex feeding system with many food chains

4. Energy pyramid a. Diagram showing how energy is transferred through a food chainb. Each level represents either a producer a consumerc. When energy is transferred from one level to another about

d. 90% of the energy is lost

B. Ecological succession

1. The tendency for ecosystems to change from simple to complex2. Primary : occurs on bare, lifeless substrates3. Secondary : occurs in areas which previously had life, but were disturbed by

some event4. Climax community: the community that is established when the succession has

stabilized5. Fugitive species : species which occur early in the successional stages and later

disappear

III. Population Dynamics

A. Population growth

1. Biotic potential: the rate at which a population will increase with no limitsa. Affected by several factors

1. Emigration: movement out of the area2. Immigration: movement into an area

b. Populations generally follow an exponential growth rate curve2. Carrying capacity:  the size at which a population stabilizes in a particular

locationa. Population stabilizing factors:

1. Space (for habitats)2. Light & water3. Nutrients

b. These result in a sigmoid growth rate curve

B. Ecological relationships that affect population size

1. Competition: when two organisms are both using a resource that is in short supply

a. Competitive exclusion1. If two species are competing for the same limited resource in the

same place, one of them will be able to use that resource more efficiently than the other and eventually will drive that second species to extinction locally

2. The excluded species can emigrate to another location in order to survive

b. Niches

1. Fundamental: the niche that an organism occupies in the absence of competitors

2. Realized: the niche that it occupies under natural conditions2. Predator-Prey  interaction

a. Predator: organism that captures other organisms for foodb. Prey: organism that is eaten by the predatorc. Populations generally follow slightly offset oscillations in their growth

curves3. Defenses to predation

a. Plants: plants will release chemicals to inhibit digestion by animalsb. Animals

1. Chemical defenses a. Some herbivores retain the plants toxins and become

poisonous themselvesb. Some animals secrete chemicals in response to attack from

predatorsc. Many animals with chemical defenses

have aposematic coloration2. Non-chemical defenses

a. Cryptic  (camouflage) coloring: to blend in with backgroundb. Mimicry: non-poisonous species displaying warning colors

C. Symbiosis

1. Def: when two organisms live together2. Mutualism : symbiosis where both organisms benefit3. Commensalism: where one organism benefits and the other is not affected4. Parasitism : symbiosis where one organism lives off of another organism (host)

IV. Biomes

A. A region with a distinct climate and the organisms that live there

B. Biomes generally blend into one another at their border

C. Biomes are determined based on the amount of annual rainfall

D. Tropical rain forest

1. High rainfall and high temperature2. High productivity despite infertile soil3. Nutrients are stored in plants and rapidly recycled

4. Almost half of all terrestrial organisms live here

E. Savanna

1. Reduced rainfall and temperature2. Typically covered with grass and scattered trees3. Transitional between tropical rain forest and desert

F. Desert

1. Low rainfall and high temperatures2. Desert plants store water (succulents) and have extensive roots3. Most animals are nocturnal (active at night) to avoid the heat4. Critical factor is water (behavior and physiology adapted to conserve water)

G. Grasslands (prairie)

1. Abundant rainfall and seasonal temperature changes2. Grasses are the most common plant (few trees)3. Grazing animals very common: horses, rabbits, cows

H. Temperate deciduous forest

1. Distinct seasons (winter, spring, summer, fall)2. Rainfall varies3. Many varieties of plants (perennial) and animals4. Chaparral: evergreen scrub-type plants common in Mediterranean-type

climates

I. Taiga (northern coniferous forests)

1. Long, cold winters with little precipitation2. Most of the precipitation occurs in the summer3. Extensive coniferous forests (pine, hemlock, fir)4. Many large animals (moose, elk, bear, deer, etc)

J. Tundra (40% of the earth's land surface)

1. Low temperatures and low rainfall2. Very short growing season3. Found at high latitudes and very cold places

4. Most of the water is trapped in the permafrost located a few feet below the surface

K. Aquatic Environments (75% of the earth's surface)

1. Neritic zone (shallow waters along coasts)a. Littoral  (intertidal) zone: exposed at low tideb. Estuaries : areas where fresh and salt water mix

1. Highest productivity of any aquatic area2. Important areas for fish hatcheries

2. Surface zone (open sea)a. Plankton : organisms that drift freely in the illuminated waterb. Nekton : larger organisms that swim in the same waterc. Rapid turnover of nutrients

3. Abyssal zone (deep water - dominated by decomposer organisms and scavengers)

4. Freshwater environments a. Limnetic (photic) zone: area of light penetrationb. Profundal (aphotic) zone: area without light penetrationc. Thermal stratification : water layering based on temperature

1. Epilimnion: warmer surface waters2. Hypolimnion: cooler deeper waters3. Thermocline: the abrupt change in temperature at the border

between the epilimnion and the hypolimniond. Seasonal overturn

1. Water achieves its maximum density at 4 C2. During winter, surface waters cool and sink removing the thermal

stratification3. This allows nutrient-rich deep water to rise to the surface4. Nutrients are now available in the spring for productivity

V. Human Influence in Ecology

A. Pollution: contaminating the environment

1. Air (smog, CFC's, etc)a. Commercial and industrial: factories, businessesb. Personal: cars, aerosal sprays, BBQ'sc. Acid rain : rain with a pH less than 5.6 (caused by air pollutants)

2. Watera. Chemical (industrial wastes, personal wastes)b. Thermal (heat): from power plants

3. Other types of pollution (noise, visual, light)4. Types of pollutants

a. Biodegradable : can be being broken down naturallyb. Non-biodegradable: cannot be broken down naturally

B. Conservation: wise and careful use of the resources

1. Renewable: capable of being replaced within a lifetime2. Non-renewable: not capable of being replaced

a. Soilb. Waterc. Non-renewable energy sources

1. Fossil fuels (coal, oil, natural gas)2. Nuclear fission reactors

VI. Global Issues in Ecology

A. Ozone depletion

1. CFC's released into the atmosphere will break down the ozone layer2. Destruction of ozone will increase the UV light reaching the earth

B. Destruction of tropical rainforest

1. Reduction in the number of species2. Soil is not very fertile and becomes unusable in a short time

C. Global warming (Greenhouse Effect)

1. Global surface temperature is thought to be increasing2. If this continues, one of the following will occur:

a. Melting of polar ice caps raising global sea levelb. Increased evaporation producing more clouds

thereby reducing temperaturesc. No scientific consensus